Co-addition of metakaolin and silica fume in mortar: effects and advantages. (10th February 2019)

• Record Type: Journal Article
• Authors: Chu, S.H.; Kwan, A.K.H.
• Is Part Of: Construction & building materials. Volume 197(2019)
• Page Start: 716
• Page End: 724
• Publication Date: 2019-02-10
• Subjects: Fresh properties -- Hardened properties -- Metakaolin -- Silica fume -- Synergistic effect; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.11.244
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Metakaolin (MK) and silica fume (SF) have been used in concrete separately. MK has +ve effect on workability but SF has −ve effect on workability. Co-addition of MK + SF increases workability to mitigate −ve effect of SF. Co-addition of MK + SF gives higher strength than sole addition of MK or SF. Co-addition of MK + SF offers synergistic effects on workability and strength. Abstract: Metakaolin (MK), ground to finer than cement, is an emerging pozzolanic material for concrete production. Silica fume (SF), which is even finer than MK, has been proven to be effective in improving the strength of concrete. Both are being added separately, but in theory, they can also be added together. To explore the possible co-addition of MK and SF and evaluate their combined effects, mortar mixes with varying water, MK and SF contents were tested for their fresh and hardened properties. From the experimental results, it was found that regarding workability, MK has positive effect, SF has negative effect, and co-addition of MK and SF can mitigate the negative effect of SF. Regarding strength, both MK and SF have positive effects, but co-addition of MK and SF has the synergistic effect that the increase in strength due to co-addition of MK and SF is larger than the increase in strength due to sole addition of MK or sole addition of SF. Such synergistic effect should be particularly useful for production of high-performance concrete.